Device for protection against bursting projectiles



June 16, 1 4 s. E. BERGE ETAL DEVICE FOR PROTECTION AGAINST BURSTING PROJECTILES Filed March 7. 1960 INVENTORS: SVEN ERIK BERGE PEHR GUNIVAR RICHARD GULDBEAND GEENANDER \SVEN EMIL PHIL/P BY ATram/s r United States Patent 3,137,205 DEVICE FOR PROTECTION AGAINST BURSTING PROJECTILES Sven Erik Berge and Pehr Gunnar Richard Guldbrand Grenander, Stockholm, and Sven Emil Philip, Nasbypark, Sweden, assignors to Aktiebolaget Bofors, Bofors, Sweden, a Swedish company Filed Mar. 7, 1960, Ser. No. 13,255 4 Claims. (Cl. 89-36) This invention relates to a device for providing combat vehicles, naval craft, fortifications, and the like objects with protection against bursting type projectiles, especially hollow charge projectiles.

It is well known that the penetration capability of hollow-charge projectiles is usually far greater than the elfect obtained with other kinds of projectiles of corresponding size. Heretofore, protection against hollowcharge projectiles, within reasonable weights and costs, has been obtained by providing screens made of thin armor plate spaced apart from the object to be protected and having protection against other kinds of armor piercing projectiles. These screens cause the projectile with a hollow-charge to burst so far from the main projection of the object that its burst cone is sufiiciently weakened before impact with the object proper and is thus incapable of piercing the main protective armor. However, such screens have been found to have certain disadvantages which allow their use to only a minor extent. For example, it has been found that only small portions of the object can be protected by such screens due to the fact that it is necessary to place them at comparatively great distances, from three to six feet, from the object such as a warship or a vehicle, for instance, a tank, if the protective effect is to be sufiicient. At such distances from the sides of the object, screens covering a large portion of the object would greatly limit the field of vision of the crew, the zone covered by the armament of the ship or vehicle, and the mobility of the ship or vehicle itself. Another disadvantage of these plate type screens is that they must absorb very great forces in relation to their strength when they are hit by shock waves of projectiles bursting in their vicinity, and can thus be easily torn oli the object they are intended to protect.

It is therefore an object of the present invention to provide a protective device for armored objects of the type described which is extremely simple in construction, efiicient in operation, and which will overcome the aforementioned difficulties.

Another object of the present invention is to provide a protective device of the above type that is especially adaptable for use with armored objects, such as combat vehicles, naval vessels, and gun turret fortifications.

A more specific object of the present invention is to provide a protective device of the class described that employs screens placed at a certain distance from the object to be protected, each such screen including a number of parallel bars of heavy construction, and connected in spaced apart parallel relationship by a minimum number of connecting members to form a sturdy grating.

Another specific object of the present invention is to provide a grating type, protective device of the aforernentioned type in which the distance between the rigid bars is approximately equal to the caliber of the smallest projectiles against which the grating is to afiord protection, so that when the point of a projectile passes between the bars, it is bound to strike one of such bars with a part of its wall, whereby the impact damage to the projectile minimizes the impact damages of the bursting charge of such projectile.

All of the foregoing and still further objects and advantages of this invention will become evident from a 3,137,205 Patented June 16, 1964 study of the following specification, taken in connection with the accompanying drawing, wherein:

FIGURE 1 is a diagrammatic side elevational view of a protective device made in accordance with the present invention in actual use mounted upon a tank;

FIGURE 2 is an enlarged fragmentary cross sectional view taken along line 2--2 of FIGURE 1, illustrating one arrangement of the present invention; and

FIGURE 3 is a view similar to FIGURE 2, of a slightly modified form of construction.

Referring now more in detail to the drawing, a protective grating 10 made in accordance with the present invention is shown to include a plurality of substantially rigid and spaced apart parallel bars 11 secured together in such spaced apart parallel relationship by a minimum number of connecting members 12. A bracket 14 secured to the grating has a base 18 with rollers 19 that is rollably supported upon a longitudinally extending support bar 16 of the tank 15 which the device 10 is to protect. Normally, the protective grating may be disposed immediately adjacent to the surface of the tank 15 which it is to protect, in the broken line position 10a, in which position it protrudes a minimum amount from the exterior surface of the vehicle and provides minimum obstruction to the visibility of the crew members and may not be readily dislodged during travel over rough terrain. However, by adjusting the position of the grating to the full line position 10, spaced further outwardly from the surface which it is to protect, the grating provides a maximum degree of protection against bursting charges of projectiles coming into contact therewith.

For a protective grating intended primarily for tanks, the open space between the bars 11 may be approximately three inches, and each such bar 11 may have a cross sectional circular area of at least one square centimeter. By making these screens in the form of gratings, it is possible to arrange them so that the field of vision of the crew of the object is not impaired to any significant degree. With consideration to this, the maximum width of the bars in the grating plane should not exceed the normal eye spacing; i.e., approximately five centimeters. Furthermore, these gratings will have but little sensitivity to shock waves generated by bursting projectiles.

It is well known that projectiles with hollow-charges are very sensitive to damages to the bursting charge. Even small cracks in the wall of the projectile can cause a considerable reduction of their effect. If there are major damages, the eliect of the projectile will be eliminated entirely. By selecting the correct spacing between the bars of the grating and the cross sectional dimension of the bars, as above, the grating will cause damage to the projectile and the bursting charge thereof in a considerable number of cases before the burst takes place, as it is quite unlikely that the point of the projectile will strike any one of the grating bars. The armor piercing capability of present day projectiles with hollow-charge may then be practically completely eliminated as present day projectiles have very thin walls. In the event that the detonator point of the projectile should strike a grating bar, in a small number of cases, the armor piercing capability will still be reduced because of the distance of the grating bars from the main armor of the object. In addition, the burst cone of the projectile will be disturbed by the presence of the grating bar which is in its way.

Because of the capability of the present invention in may cases to eliminate partly or entirely the hollow-charge effect, grates according to the present invention afford an essential reinforcement of the armor protection, even when placed at much shorter distances from the main armor than required with plate type screens. Thus, it may be appropriate, where the object requires great mobility,

to retract the grates in the manner shown in broken lines in FIGURE 1, when the object is being moved, in which retracted position, there is still afforded a certain degree of protection. It may thus be possible to extend-the protective grating outwardly to the full line position whenever combat is expected in order to obtain maximum protection.

In the embodiment shown in FIGURE 2 of the drawing, each of the bars 11 is of generally circular cross sectional configuration. In the arrangement 20 shown in FIGURE 3, each of the bars 21 is of a tapered cross section, having an apex 23 facing outwardly in a direction away from the object which it is to protect. In this embodiment, a minimum number of connecting members 22 is also employed in order to prevent interference With the visibility of the crew members, as above explained. In both embodiments of the present invention, the dimension d is approximately equal to the caliber of the smallest projectiles against which the grating is intended to alford protection. While the embodiment illustrated in FIGURE 3 of the drawing involves somewhat higher costs than those of the embodiment shown in FIGURE 2, better protection is provided against bursting charges of projectiles which hit the screen from a direction approximately at right angles to the plane of the screen; i.e., a direction in which the projectile gives the maximum armor piercing effect.

The bars in a protective device made in accordance with the present invention may be placed in an arbitrary direction. However, in cases where the field of vision is important, it is appropriate to place them at right angles to a horizontal line. The members 12,22, by means of which the bars 11, 21, respectively, are held together to form the grating should be as few as possible so that they offer the least possible impact surface for the percussion point of the projectile.

It will also be recognized that aside from affording protection against hollow-charge projectiles, the present invention may also be used as a protective device against the bursting effects of other kinds of projectiles, such as squash-head shells and ordinary high explosive shells, as the detonation point of any such shell striking the grating will be at a distance from the main armor of the object being protected, thus substantially reducing the damaging effects thereof.

While this invention has been described with particular reference to the construction shown in the drawing, it is to be understood that such is not to be construed as imparting limitations upon the invention, which is best defined by the claims appended hereto.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. A protective device for reducing the piercing action of explosive projectiles of the hollow charge type upon a target surface, said device comprising a grating formed by a plurality of parallel, rigid, metal bars spaced apart by a distance greater than the cross-sectional width of the bars, and support means supporting said grating for displacement of the same in planes parallel to the target surface between an inactive position of the grating in which the bars thereof are closely adjacent to the target surface and a protective position in which the bars are spaced apart from said target surface by a selected distance.

2. A protective device according to claim 1 wherein said bars have a generally circular cross-section.

3. A protective device according to claim 1 wherein connecting members extending transversely across said bars secure the same in said spaced apart parallel positions, the number of said bars being greatly in excess of that of said connecting members.

4. A protective device according to claim 1 wherein said bars have a generally conical cross-section, the apex of each bar facing away from the target surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,200,230 Hojnowski May 7, 1940 FOREIGN PATENTS 706,318 Germany May 23, 1941 127,321 Great Britain June 5, 1919 1,041,126 France May 27, 1953 1,103,549 France May 25, 1955 OTHER REFERENCES Strange As It Seems, John Hix, Richmond Times- Dispatch, Sept. 27, 1942. 

1. A PROTECTIVE DEVICE FOR REDUCING THE PIERCING ACTION OF EXPLOSIVE PROJECTILES OF THE HOLLOW CHARGE TYPE UPON A TARGET SURFACE, SAID DEVICE COMPRISING A GRATING FORMED BY A PLURALITY OF PARALLEL, RIGID, METAL BARS SPACED APART BY A DISTANCE GREATER THAN THE CROSS-SECTIONAL WIDTH OF THE BARS, AND SUPPORT MEANS SUPPORTING SAID GRATING FOR DISPLACEMENT OF THE SAME IN PLANES PARALLEL TO THE TARGET SURFACE BETWEEN AN INACTIVE POSITION OF THE GRATING IN WHICH THE BARS THEREOF ARE CLOSELY ADJACENT TO THE TARGET SURFACE AND A PROTECTIVE POSITION IN WHICH THE BARS ARE SPACED APART FROM SAID TARGET SURFACE BY A SELECTED DISTANCE. 